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| author | Sergey Senozhatsky <senozhatsky@chromium.org> | 2023-04-15 19:01:10 +0900 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-04-25 21:03:14 -0400 |
| commit | 96928d9032a7c34f12a88df879665562bcebf59a (patch) | |
| tree | b25e52ee726d90ad73a4591b2eafa67d5cd3ae85 | |
| parent | c7bdb07902e0b633795372665d0154e7267ecd0e (diff) | |
| download | lwn-96928d9032a7c34f12a88df879665562bcebf59a.tar.gz lwn-96928d9032a7c34f12a88df879665562bcebf59a.zip | |
seq_buf: Add seq_buf_do_printk() helper
Sometimes we use seq_buf to format a string buffer, which
we then pass to printk(). However, in certain situations
the seq_buf string buffer can get too big, exceeding the
PRINTKRB_RECORD_MAX bytes limit, and causing printk() to
truncate the string.
Add a new seq_buf helper. This helper prints the seq_buf
string buffer line by line, using \n as a delimiter,
rather than passing the whole string buffer to printk()
at once.
Link: https://lkml.kernel.org/r/20230415100110.1419872-1-senozhatsky@chromium.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | include/linux/seq_buf.h | 2 | ||||
| -rw-r--r-- | lib/seq_buf.c | 32 |
2 files changed, 34 insertions, 0 deletions
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h index 5b31c5147969..515d7fcb9634 100644 --- a/include/linux/seq_buf.h +++ b/include/linux/seq_buf.h @@ -159,4 +159,6 @@ extern int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary); #endif +void seq_buf_do_printk(struct seq_buf *s, const char *lvl); + #endif /* _LINUX_SEQ_BUF_H */ diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 0a68f7aa85d6..45c450f423fa 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -93,6 +93,38 @@ int seq_buf_printf(struct seq_buf *s, const char *fmt, ...) } EXPORT_SYMBOL_GPL(seq_buf_printf); +/** + * seq_buf_do_printk - printk seq_buf line by line + * @s: seq_buf descriptor + * @lvl: printk level + * + * printk()-s a multi-line sequential buffer line by line. The function + * makes sure that the buffer in @s is nul terminated and safe to read + * as a string. + */ +void seq_buf_do_printk(struct seq_buf *s, const char *lvl) +{ + const char *start, *lf; + + if (s->size == 0 || s->len == 0) + return; + + seq_buf_terminate(s); + + start = s->buffer; + while ((lf = strchr(start, '\n'))) { + int len = lf - start + 1; + + printk("%s%.*s", lvl, len, start); + start = ++lf; + } + + /* No trailing LF */ + if (start < s->buffer + s->len) + printk("%s%s\n", lvl, start); +} +EXPORT_SYMBOL_GPL(seq_buf_do_printk); + #ifdef CONFIG_BINARY_PRINTF /** * seq_buf_bprintf - Write the printf string from binary arguments |